Dispersant and dispersant viscosity index improvers from selectively hydrogenated aryl-substituted olefin containing diene copolymers

ABSTRACT

The invention provides dispersants and dispersant viscosity index improvers which include polymers of conjugated dienes which have been hydrogenated, functionalized, optionally modified, and post treated. The dispersant substances include a copolymer of two different conjugated dienes and an aryl-substituted olefin. The polymers are selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization. Also provided are lubricant fluids, such as mineral and synthetic oils, which have been modified in their dispersancy and/or viscometric properties by means of the dispersant substances of the invention. Also provided are methods of modifying the dispersancy and/or viscometric properties of lubricating fluids such as mineral and synthetic lubricating oils. The dispersant substances may also include a carrier fluid to provide dispersant concentrates.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation in part of U.S. application Ser. Nos.09/102,597, 09/102,680, now U.S. Pat. Nos. 6,162,768 and 6,034,184,09/102,681, and 09/102,718 now U.S. Pat. No. 6,103,676 all filed on Jun.23, 1998, which are a continuation in part of U.S. application Ser. No.09/127,073, now U.S. Pat. No. 6,054,539 filed Jul. 31, 1998, U.S.application Ser. No. 08/734,982, filed Oct. 22, 1996, and now U.S. Pat.No. 5,780,540, which is a continuation in part of U.S. application Ser.No. 08/488,046, filed Jun. 7, 1995, and now U.S. Pat. No. 5,633,415, andU.S. application Ser. No. 08/476,016, filed Jan. 7, 1995, and now U.S.Pat. No. 5,637,783, both of which are a continuation in part of U.S.application Ser. No. 08/382,814, filed Feb. 3, 1995, and now U.S. Pat.No. 5,545,783, which is a divisional of U.S. application Ser. No.08/179,051 filed Jan. 7, 1994, and now U.S. Pat. No. 5,387,730, which isa divisional of U.S. application Ser. No. 07/992,341, filed Dec. 17,1992, and now U.S. Pat. No. 5,288,937, which is a continuation of U.S.application Ser. No. 07/907,959 filed Aug. 6, 1992, and now U.S. Pat.No. 5,210,359, which is a divisional of U.S. application Ser. No.07/466,135 filed Jan. 16, 1990, and now U.S. Pat. No. 5,149,895. Theentire contents of U.S. application Ser. No. 07/466,135 are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

This invention relates to dispersants, dispersants with improved engineperformance, dispersants with viscosity index (VI) improving properties,and dispersant VI improvers from functionalized diene polymers, andmethods of their use. More particularly, the invention relates todispersants, dispersants with VI improving properties, and dispersant VIimprovers from selectively hydrogenated copolymers prepared usingconjugated dienes. The invention is additionally directed todispersants, dispersants with VI improving properties, and dispersant VIimprovers from chemically modified derivatives of the above polymers.

Liquid elastomers are well known and are used in various applications.For example, many functionally terminated polybutadiene liquidelastomers are known. These materials are generally highly unsaturatedand frequently form the base polymer for polyurethane formulations. Thepreparation and application of hydroxy-terminated polybutadiene isdetailed by J. C. Brosse et al. in Hydroxyl-terminated polymers obtainedby free radical polymerization—Synthesis, characterization andapplications, Advances in Polymer Science 81, Springer-Verlag, Berlin,Heidelberg, 1987, pp. 167-220.

Also, liquid polymers possessing acrylate, carboxy- ormercapto-terminals are known. In addition to butadiene, it is known toutilize isoprene as the base monomer for the liquid elastomers. Theliquid elastomers may contain additional monomers, such as styrene oracrylonitrile, for controlling compatibility in blends with polarmaterials, such as epoxy resins.

Also known in the prior art are pure hydrocarbon, non-functionalizedliquid rubbers. These liquid elastomers contain varying degrees ofunsaturation for utilization in vulcanization. Typical of highlyunsaturated liquid elastomers is polybutadiene, e.g., that sold underthe name RICON by Ricon Resins, Inc. A liquid polyisoprene which hasbeen hydrogenated to saturate 90% of its original double bonds ismarketed as LIR-290 by Kuraray Isoprene Chemical Co. Ltd. Still morehighly saturated are liquid butyl rubbers available from Hardman RubberCo., and Trilene, a liquid ethylene-propylene-diene rubber (EPDM)available from Uniroyal Chemical Co. The more highly saturated liquidelastomers exhibit good oxidation and ozone resistance properties.

Falk, Journal of Polymer Science: PART A-1, 9:2617-23 (1971), the entirecontents of which are incorporated herein by reference, discloses amethod of hydrogenating 1,4,-polybutadiene in the presence of1,4-polyisoprene. More particularly, Falk discloses hydrogenation of the1,4-polybutadiene block segment in the block copolymer of1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene and in randomcopolymers of butadiene and isoprene, with both polymerized monomershaving predominantly 1,4-microstructure. Hydrogenation is conducted inthe presence of hydrogen and a catalyst made by the reaction oforganoaluminum or lithium compounds with transition metal salts of2-ethylhexanoic acid. Falk, Die Angewandte Chemie, 21(286):17-23 (1972),the entire contents of which are also incorporated herein by reference,discloses the hydrogenation of 1,4-polybutadiene segments in a blockcopolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene.

Hoxmeier, Published European Patent Application 88202449.0, filed onNov. 2, 1988, Publication Number 0 315 280, published on May 10, 1989,discloses a method of selectively hydrogenating a polymer made from atleast two different conjugated diolefins. One of the two diolefins ismore substituted in the 2, 3 and/or 4 carbon atoms than the otherdiolefin and produces tri- or tetra-substituted double bond afterpolymerization. The selective hydrogenation is conducted under suchconditions as to hydrogenate the ethylenic unsaturation incorporatedinto the polymer from the lesser substituted conjugated diolefin, whileleaving unsaturated at least a portion of the tri- or tetra-substitutedunsaturation incorporated into the polymer by the more substitutedconjugated diolefin.

Mohajer et al., Hydrogenated linear block copolymers of butadiene andisoprene: Effects of variation of composition and sequence architectureon properties, Polymer 23:1523-35 (1982) discloses essentiallycompletely hydrogenated butadiene-isoprene-butadiene (HBIB), HIBI andHBI block copolymers in which butadiene has predominantly1,4-microstructure.

Kuraray K K, Japanese published patent application Number JP-328 729,filed on Dec. 12, 1987, published on Jul. 4, 1989, discloses a resincomposition comprising 70-99% wt. of a polyolefin (preferablypolyethylene or polypropylene) and 1-30% wt. of a copolymer obtained byhydrogenation of at least 50% of unsaturated bond of isoprene/butadienecopolymer.

Ashless dispersants are additives to lubricant fluids such as fuels andlubricating oils which improve the dispersability of the fluids orimprove their viscometric properties. Typically, such dispersants aremodified polymers, having an oleophilic polymer backbone to assure goodsolubility and to maintain particles suspended in the oil, and polarfunctionality to bind or attach to oxidation products and sludge.Dispersants generally have a solubilizing oleophilic (hydrophobic) tailand a polar (hydrophilic) head, forming micelles when actively bound tosludge.

Common dispersants include polyisobutenes which have been modified bythe ene reaction to include functional groups such as succinimides,hydroxyethyl imides, succinate esters/amides, and oxazolines. Otherdispersants include Mannich base derivatives of polybutenes, ethylenepropylene polymers, and acrylic polymers.

Traditionally, dispersants have been polybutenes functionalized at onesite in the molecule via an ene reaction with maleic anhydride followedby imidization with a polyamine. The polybutenes are typically 500-2,000in molecular weight, and due to the polymerization process employed intheir manufacture, have no more than one double bond per polybutenemolecule. Accordingly, the number of potential functional groups perchain is limited to about one. Typically, this site is at a terminalportion of the molecule. Moreover, it is generally accepted that, inorder to obtain beneficial dispersant properties, a molecule must haveat least one functional group per approximately 2,000 molecular weight.Consequently, the molecular weight of traditional polybutene dispersantscannot exceed 2,000 if the desired functionality/hydrocarbon ratio is tobe maintained. In addition, traditional dispersants have had molecularstructures which have limited the placement of functional groups,generally requiring that such groups be placed at the terminal regionsof the molecules.

The polymerization process for the traditional butene polymers has alsogenerated products having an unacceptably wide distribution of molecularweights, i.e., an unacceptably high ratio of weight average molecularweight (M_(w)) to number average molecular weight (M_(n)). Typically,such distributions are M_(w)/M_(n)≧2.5, producing compositions whosedispersant properties are not well defined.

Moreover, functionalization reactions in these polymers have typicallyyielded substantial quantities of undesirable by-products such asinsoluble modified polymers of variant molecular weight.Functionalization reactions can also result in compounds which containundesirable chemical moieties such as chlorine.

U.S. Pat. No. 4,007,121 to Holder et al. describes lubricant additiveswhich include polymers such as ethylene propylene polymers (EPT) havingN-hydrocarbylcarboxamide groups.

U.S. Pat. Nos. 3,868,330 and 4,234,435 to Meinhardt et al. disclosecarboxylic acid acylating agents for modification of lubricantadditives. Modified polyalkenes are described such aspolyisobutene-substituted succinic acylating agents having M_(n) of1300-5000 and M_(w)/M_(n) of 1.5-4. These processes employ chlorinationto provide greater functionality.

Heretofore, the art has failed to produce dispersants and dispersant VIimprovers having selective and controllable amounts of polarfunctionality in their polymeric structure. Thus, the art has failed toprovide any means of developing dispersants and dispersant VI improvershaving higher molecular weights and/or higher amounts offunctionalization per molecule. The art has also failed to providedispersant polymers having desirably narrow molecular weightdistributions to avoid the presence of by-products which degradedispersant performance. The art has also failed to provide dispersantand VI improving compositions which exhibit good thermal stability.

Accordingly, it is a purpose of this invention to provide dispersantsand dispersant VI improvers having polymeric structures which permithighly selective control of the degree of unsaturation and consequentfunctionalization. Unique materials can also be obtained by chemicalmodification of the polymers of this invention since the polymers can beselectively modified at controllable sites, such as at random sites orat the terminal ends of the molecules.

It is an additional purpose of this invention to provide a method forthe production of dispersants and dispersant VI improvers from polymershaving controlled amounts of unsaturation incorporated randomly in anotherwise saturated backbone. In contrast to EPDM-based dispersants, thelevel of unsaturation can be inexpensively and easily controlled, e.g.,from 1% to 50%, to provide a wide variation in functionalizability.

It is a further purpose of the invention to provide dispersant and VIimproving polymers having narrow molecular weight distributions and aconcomitant lack of undesirable by-products, thereby providing moreprecisely tailored dispersant and/or VI improving properties.

It is still a further purpose of this invention to provide dispersantshaving improved engine performance.

SUMMARY OF THE INVENTION

The invention provides dispersant and dispersant Viscosity index (VI)improvers which include polymers of conjugated dienes which have beenhydrogenated, functionalized, optionally modified, and post treated. Thedispersancy and VI improving properties of the compositions of theinvention may be controlled by controlling the size of the polymers andthe extent and distribution of their functionalization. Accordingly,these substances are termed throughout “dispersant substances”.

In one embodiment of the invention, there is provided a dispersantsubstance for modifying the dispersancy or viscometric properties of alubricant fluid, in which the dispersant substance includes a copolymerof two different conjugated dienes. In this case, the first conjugateddiene includes at least one relatively more substituted conjugated dienehaving at least five carbon atoms and the formula:

wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that atleast one of R¹-R⁶ is a hydrocarbyl group, and also provided that, afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (1) has the formula:

wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups.

The second conjugated diene in the dispersant substances of hisembodiment includes at least one relatively less substituted conjugateddiene which is different from the first conjugated diene and has atleast four carbon atoms and the formula:

wherein R⁷-R¹² are each hydrogen or a hydrocarbyl group, provided that,after polymerization, the unsaturation of the polymerized conjugateddiene of formula (3) has the formula:

wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group.

Following polymerization the diene copolymer is selectively hydrogenatedand subsequently functionalized to provide a functionalized copolymerhaving at least one polar functional group.

The functionalized copolymer is optionally modified by reaction with aLewis base selected from the group consisting of a monoamine, polyamine,polyhydroxy compound, reactive polyether, or a combination thereof.

The copolymer is then post treated with a post treating agent, forexample a boron-containing compound.

In a preferred embodiment, the dispersant substance includes a polymerin which the first and second conjugated dienes are polymerized as ablock copolymer including at least two alternating blocks:

(I)_(x)-(B)_(y) or (B)_(y)-(I)_(x)

In this case, the block (I) includes at least one polymerized conjugateddiene of formula (1), while the block (B) includes at least onepolymerized conjugated diene of formula (3). In addition, x is thenumber of polymerized monomer units in block (I) and is at least 1, andy is the number of polymerized monomer units in block (B) and is atleast 25. It should be understood throughout that x and y are definedrelative to blocks in a linear block copolymer or blocks in an arm orsegment of a branched or star-branched copolymer in which the arm orsegment has substantially linear structure.

Preferably, in the block copolymers of this embodiment, x is from about1 to about 600, and y is from about 30 to about 4,000, more preferably xis from about 1 to about 350, and y is from about 30 to about 2,800.While larger values for x and y are generally related to largermolecular weights, polymers which have multiple blocks and star-branchedpolymers typically will have molecular weights which are not wellrepresented in the values of x and y for each block.

Alternatively, the dispersant substance includes the first and secondconjugated dienes polymerized as a random copolymer. The dispersantsubstance may include the first and second conjugated dienes polymerizedas a branched or star-branched copolymer.

The copolymers useful according to this embodiment typically have amolecular weight of at least about 2,000. Preferably, the molecularweight of these polymers is from about 2,000 to about 1,000,000, morepreferably from about 5,000 to about 500,000.

The molecular weight of a polymer of the invention is generallyassociated with the physical properties it exhibits hen employed as adispersant or dispersant VI improver. Typically, polymers having lowermolecular weights are employed as dispersants, while VI-improvingproperties and relative thickening power are associated with polymershaving higher molecular weights and correspondingly greater viscosity.For purposes of discussion, polymers of the invention having molecularweights in the range of from about 2,000 to about 20,000 may beclassified as dispersants, polymers having molecular weights of fromabout 20,000 to about 50,000 may be classified as dispersants withVI-improving properties, and polymers having molecular weights of about50,000 or more may be classified as dispersant VI improvers.

In the dispersant substances of the invention, the copolymer ispreferably selectively hydrogenated. It is preferred that theunsaturation of formula (4) be substantially completely hydrogenated,thereby retaining substantially none of the original unsaturation ofthis type, while the unsaturation of formula (2) is substantiallyretained (i.e., the residual unsaturation after hydrogenation), in atleast an amount which is sufficient to permit functionalization of thecopolymer.

After the hydrogenation reaction, the Iodine Number for the residualunsaturation of formula (2) is generally from about 50% to about 100% ofthe Iodine Number prior to the hydrogenation reaction. More preferably,after hydrogenation, the Iodine Number for the residual unsaturation offormula (2) is about 100% of the Iodine Number prior to thehydrogenation reaction.

After the hydrogenation reaction, the Iodine Number for the residualunsaturation of formula (4) is from about 0% to about 10% of the IodineNumber prior to the hydrogenation reaction. More preferably, after thehydrogenation reaction, the Iodine Number for the residual unsaturationof formula (4) is from about 0% to about 0.5% of the Iodine Number priorto the hydrogenation reaction. Most preferably, after the hydrogenationreaction, the Iodine Number for the residual unsaturation of formula (4)is from about 0% to about 0.2% of the Iodine Number prior to thehydrogenation reaction.

The conjugated diene of formula (1) preferably includes a conjugateddiene such as isoprene, 2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene,myrcene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof. More preferably, the conjugated diene of formula(1) includes isoprene, myrcene, 2,3-dimethyl-butadiene or2-methyl-1,3-pentadiene. Still more preferably, the conjugated diene offormula (1) includes isoprene.

Preferably, the conjugated diene of formula (3) includes 1,3-butadiene,1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene,1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadiene,2,4-nonadiene, 3,5-nonadiene, 1,3-decadiene, 2,4-decadiene,3,5-decadiene, or mixtures thereof. More preferably, the conjugateddiene of formula (3) includes 1,3-butadiene, 1,3-pentadiene, or1,3-hexadiene. Still more preferably, the conjugated diene of formula(3) includes 1,3-butadiene.

Generally, when the conjugated diene includes substantial amounts of1,3-butadiene, the polymerized butadiene includes a mixture of 1,4- and1,2-units. The preferred structures contain at least about 25% of the1,2-units. More preferably, the structures contain from about 30% toabout 90% of the 1,2-subunits. Most preferably, the structures containfrom about 45% to about 65% of the 1,2-units.

To provide dispersancy, the selectively hydrogenated polymer ischemically modified (functionalized) to provide a polymer having atleast one polar functional group, such as, but not limited to, halogen,epoxy, hydroxy, amino, nitrilo, mercapto, imido, carboxy, and sulfonicacid groups of combinations thereof. The functionalized polymers can befurther modified to give a more desired type of functionality.

In a preferred case, the selectively hydrogenated polymer isfunctionalized by a method which includes: reacting the selectivelyhydrogenated polymer with an unsaturated carboxyilic acid (or derivativethereof, such as maleic anhydride) to provide an acylated polymer, andthen reacting the acylated polymer with a monoamine, a polyamine, apolyhydroxy compound, a reactive polyether, or a combination thereof.

The modified polymer is contacted with one or more post treating agents.

Any of the dispersant substances of the invention may include afunctionalized polymer of the invention distributed in a carrier fluidsuch as a synthetic or mineral oil, to provide a dispersant concentrate.The dispersant concentrates generally include the polymer in an amountof from about 5% wt. to about 90% wt., more preferably from about 10%wt. to about 70% wt., of the dispersant substance, depending upon themolecular weight of the polymer.

The dispersant substances may further include at least one additiveselected from the group consisting of antioxidants, pour pointdepressants, detergents, dispersants, friction modifiers, anti-wearagents, anti-foam agents, corrosion and rust inhibitors, Viscosity indeximprovers, and the like.

The invention further provides a method of modifying the dispersancy orviscometric properties of a fluid such as a lubricant. The methodincludes admixing with a fluid an amount of a dispersant substance ofthe invention which is sufficient to provide a dispersant-modified fluidhaving dispersancy or viscometric properties which are altered from theoriginal fluid. Preferably, the method involves admixing the dispersantsubstance in an amount of from about 0.001% wt. to about 20% wt., morepreferably from about 0.1% wt. to about 10% wt., and most preferablyfrom about 0.5% wt. to about 7% wt., of the dispersant-modified fluid.Typically, the method of the invention is employed to modify lubricatingoils and normally liquid fuels; such as motor oils, transmission fluids,hydraulic fluids, gear oils, aviation oils, and the like. In addition,the method may further include admixing with the fluid at least oneadditive such as antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, anti-foam agents,corrosion and rust inhibitors, viscosity index improvers, and the like.

The invention also provides a dispersant-modified fluid, such as ahydrocarbon fluid, having modified dispersancy or viscometricproperties. In this embodiment, the dispersant-modified fluid typicallyincludes a mineral or synthetic oil and a dispersant substance of theinvention. Preferably, the dispersant-modified fluid of the inventionincludes a dispersant substance in an amount of from about 0.001% wt. toabout 20% wt., more preferably from about 0.1% wt. to about 10% wt., andmost preferably from about 0.5% wt. to about 7% wt., of the modifiedlubricating fluid. The dispersant-modified fluid preferably includes amineral or synthetic lubricating oil or a normally liquid fuel; such asmotor oils, transmission fluids, hydraulic fluids, gear oils, aviationoils, and the like. These dispersant-modified fluids may further includeat least one additive such as antioxidants, pour point depressants,detergents, dispersants, friction modifiers, anti-wear agents, anti-foamagents, corrosion and rust inhibitors, viscosity index improvers, andthe like.

The polymers are prepared under anionic polymerization conditions.Following polymerization, the polymers of the invention are selectivelyhydrogenated to provide a controlled amount and extent of residualunsaturation. After the selective hydrogenation reaction, thehydrogenation catalyst is removed from the polymer and the polymer ischemically modified or functionalized to impart desirablecharacteristics for the dispersant substances of the invention.

Accordingly, as a result of the invention, there are now provideddispersants, dispersants with VI-improving properties, and dispersant VIimprovers prepared by polymerization of conjugated dienes, followed byselective hydrogenation and functionalization. These dispersantsubstances of the invention possess numerous advantages, includingimproved engine performance, controlled molecular weight, controlledmolecular weight distribution, controlled polymer structure, variableand controlled amounts and distribution of functionality, superiorthermal stability, potentially permitting reduced treat levels andyielding benefits such as improved viscometric properties.

These and other advantages of the present invention will be appreciatedfrom the detailed description and examples which are set forth herein.The detailed description and examples enhance the understanding of theinvention, but are not intended to limit the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The polymeric dispersants of the invention, typically having lowermolecular weights, can be employed in any lubricant or fuel compositionthat requires a dispersant to control the deposition of sludge particleson, for example, engine parts. Other polymeric substances of theinvention, typically those having higher molecular weights, may beemployed for their VI-improving properties in any lubricant fluid whichmay benefit from a modification of its viscometric properties. Thesecompounds may also find a variety of uses in addition to lubricantadditives, such as adhesives, sealants, impact modifiers, and the like.

As noted above, traditional dispersants have been polybutenesfunctionalized via an ene reaction with maleic anhydride followed byimidization with a polyamine. The polybutenes are typically 500-2,000 inmolecular weight. With one olefin per polybutene molecule, the number ofpotential functional groups per chain is limited to one. Consequently,the molecular weight of polybutene may not exceed 2,000 if the desiredfunctionality/hydrocarbon ratio is to be maintained.

By contrast, with this invention, the amount of residual unsaturationcan be controllably varied. As a result, the amount of functionality onewishes to incorporate is quite flexible. In addition, the molecularweight of the polymer backbone is not limited to 2,000. Higher molecularweight polymers can be prepared and functionalized such that the samefunctionality/hydrocarbon ratio that is found in the traditionaldispersant is maintained if so desired. Moreover, with this invention,the position of the functionality is not limited to the end of thepolymer chain as it is with polybutenes. Instead, a variety of optionsis now available, including, for example, randomly along the backbone,at one end, at both ends, or in the center, of the polymer chain.

If a polymer according to the invention is of sufficiently highmolecular weight (e.g., 20,000-50,000), it will exhibit increasedthickening power and viscosity index-improving (VI-improving)properties, as well as sludge dispersing ability. Hence, the use ofthese materials may permit reduction in use of both traditionaldispersants and VI. If materials are prepared with backbones that are50,000 in molecular weight, the functionalized versions can beclassified as dispersant VI improvers or VI improvers with dispersantproperties. Their dispersant capabilities are outstanding for dispersantVI improvers.

In one embodiment, the present invention provides polymers including atleast two different conjugated dienes, wherein one of the dienes is moresubstituted in the 2, 3, and/or 4 carbon positions than the other diene.The more substituted diene produces vinylidene, tri-, ortetra-substituted double bonds after polymerization. Hydrogenation ofthe material is done selectively so as to saturate the lessersubstituted olefins, which primarily arise from the lesser substituteddiene, while leaving a portion of the more substituted conjugatedolefins behind for functionalizing.

In this embodiment, the more substituted conjugated diene will have atleast five (5) carbon atoms and the following formula:

wherein R¹-R⁶ are each hydrogen (H) or a hydrocarbyl group, providedthat at least one of R¹-R⁶ is a hydrocarbyl group. After polymerization,the unsaturation in the polymerized conjugated diene of formula (1) hasthe following formula:

wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups.Examples of conjugated dienes of formula 1 include isoprene,2,3-dimethylbutadiene, 2-methyl-1,3-pentadiene, myrcene, and the like.Isoprene is highly preferred.

The lesser substituted conjugated diene in this embodiment differs fromthe other diene in that it has at least four (4) carbon atoms and thefollowing formula:

wherein R⁷-R¹² are each hydrogen or a hydrocarbyl group. Afterpolymerization, the unsaturation in the polymerized conjugated diene offormula (3) has the following formula:

wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group. Examples of the conjugateddiene of formula (3) include 1,3-butadiene, 1,3-pentadiene,2,4-hexadiene, and the like. A highly preferred conjugated diene offormula 3 is 1,3-butadiene.

An exception to this scheme would be when a tetra-substituted diene,e.g., 2,3-dimethylbutadiene, is used for the more substituted component.When this occurs, a tri-substituted olefin, e.g. isoprene, may be usedfor the lesser substitued component, such that one or both of R^(V) andR^(VI) are hydrogen and both R^(VII) and R^(VIII) are hydrocarbyl.

It will be apparent to those skilled in the art that in the originalunsaturation of formula (2), R^(I), R^(II), R^(III) and R^(IV) may allbe hydrocarbyl groups, whereas in the original unsaturation of formula(4) at least one of R^(V), R^(VI), R^(VII) and R^(VIII) must be ahydrogen.

The hydrocarbyl group or groups in the formula (1) to (4) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or anyisomers thereof.

The copolymers of this embodiment are prepared by anionicallypolymerizing a diene of formula (1) at a level of from about 0.5% wt. toabout 25% wt.,and a diene of formula (3) at a level of from about 75%wt. to about 99.5% wt., in a hydrocrabon solvent using an alkyllithiumcatalyst. The two monomers can be polymerized in block, tapered block,or random fashion. Since the polymerization is anionic, the molecularweight distribution of these copolymers is typically very narrow,generally ranging from about 1.01 to about 1.20, and the molecularweight is determined by the ratio of monomer to initiator and/or by thepresence of coupling agents. The monomers (1) and (3) may be polymerizedeither simultaneously or in stepwise fashion depending on the desiredposition of the remaining unsaturation after hydrogenation. If randompositioning of the unsaturation is desired, both monomers are reactedtogether to give a random copolymer. If it is desirable to have thefunctionality on only one end, then the monomers are reacted in stepwisefashion, the order being determined as desired, to provide a diblockcopolymer. If functionality is needed on both ends, then a conjugateddiene of formula (1) is polymerized first, followed by a diene offormula (3). To the living anion, a coupling agent, e.g., phenylbenzoate or methyl benzoate, is then added to yield a desired triblockcopolymer. Alternatively, a diene of formula (1) may be added to theliving diblock to give the triblock.

A fourth approach would allow the functionality to be positioned in thecenter of the polymer chain. In this case, a diene of formula (3) ispolymerized first, followed by a diene of formula (1). Then a triblockis formed by addition of a coupling agent or by addition of more dieneof formula (3). In addition, combinations of the above approaches may beemployed.

The invention can include polymers of differing microstructures. Thepresence of polar modifier increases the activity of the catalyst and,therefore, increase the level of 1,2-microstructure over1,4-microstructure in polybutadiene, for example. The percentage ofvinyl obtained is directly proportional to the concentration of themodifier employed. Since the reaction temperature also plays a role indetermining the microstructure of polybutadiene, the level of modifiermust be chosen taking into account the combined effects. Antkowiak etal., Temperature and Concentration Effects on Polar-modified AlkylLithium Polymerizations and Copolymerizations, Journal of PolymerScience: Part A-1, 10:1319-34 (1972), incorporated herein by referencehave presented a way for quickly determining the proper conditions forpreparation of any 1,2-microstructure content within a range of fromabout 10% to about 80%. Use of this method or any others to achieve thedesired microstructure will be known to anyone who is skilled in theart.

The dispersants and dispersant VI improvers of the invention can includedifferent polymer macrostructures. Polymers may be prepared and utilizedhaving linear and/or nonlinear, e.g., star-branched, macrostructures.The star-branched polymers can be prepared by addition of divinylbenzeneor the like to the living polymer anion. Lower levels of branching canbe obtained through the use of tri-functional or tetra-functionalcoupling agents, such as tetrachlorosilane.

In all embodiments of this invention, whenever a reference is made tothe “original double bond” or the “original unsaturation” of the blockor random polymer (or copolymer), it is understood to mean the doublebond(s) in the polymer prior to the hydrogenation reaction. By contrast,the terms “residual double bond(s)” and “residual unsaturation”, as usedherein, refer to the unsaturated group(s), typically excluding aromaticunsaturation, present in the copolymer after the selective hydrogenationreaction.

The molecular structure of the original or residual double bonds can bedetermined in any conventional manner, as is known to those skilled inthe art, e.g., by infrared (IR) or nuclear magnetic resonance (NMR)analysis. In addition, the total original or residual unsaturation ofthe polymer can be quantified in any conventional manner, e.g., byreference to the Iodine Number of the polymer.

In any polymers of any of the embodiments of this invention, themicrostructure of the polymerized conjugated diene of formula (3) mustbe such that the polymer is not excessively crystalline after theselective hydrogenation reaction. That is, after the selectivehydrogenation reaction the polymer must retain its elastomericproperties, e.g., the polymer should contain not more than about 10% ofpolyethylene crystallinity. Generally, problems of crystallinity occuronly when the polymer includes polymerized 1,3-butadiene. Limitingpolymeric crystallinity may be accomplished in various ways. Forexample, this is accomplished by introducing side branches into thepolymerized conjugated dienes of formula (1) and/or (3), e.g., bycontrolling the microstructure of 1,3-butadiene if it is the predominantmonomer in the diene of formula (3); by using a mixture of dienes offormula (3) containing less than predominant amounts of 1,3-butadiene;or by using a single diene of formula (3), other than 1,3-butadiene.More particularly, if the conjugated diene(s) of formula (3) ispredominantly (at least 50% by mole) 1,3-butadiene, the side branchesare introduced into the polymer by insuring that the polymerized dieneof formula (3) contains a sufficient amount of the 1,2-units to preventthe selectively hydrogenated polymer from being excessively crystalline.Thus, if the conjugated diene of formula (3) is predominantly (at least50% by mole, e.g., 100% by mole) 1,3-butadiene, the polymerized diene offormula (3), prior to the selective hydrogenation reaction, must containnot more than about 75% wt., preferably from about 10% wt. to about 70%wt., and most preferably from about 35% wt. to about 55% wt. of the1,4-units, and at least about 25% wt., preferably from about 30% wt. toabout 90% wt., and most preferably from about 45% wt. to about 65% wt.of the 1,2-units. If the polymerized diene(s) of formula (3) containsless than 50% by mole of 1,3-butadiene, e.g., 1,3-pentadiene is used asthe only diene of formula (3), the microstructure of the polymerizeddiene of formula (3) prior to the selective hydrogenation reaction isnot critical since, after hydrogenation, the resulting polymer willcontain substantially no crystallinity.

In all embodiments of the invention, mixtures of dienes of formula (1)or (3) may be used to prepare block copolymers (I)_(x)-(B)_(y) or any ofthe random copolymers or star-branched block and random polymers of theinvention. Similarly, mixtures of aryl-substituted olefins may also beused to prepare block, random, or star-branched copolymers of thisinvention. Accordingly, whenever a reference is made herein to a dieneof formula (1) or (3), or to an aryl-substituted olefin, it mayencompass more than one diene of formula (1) or (3), respectively, andmore than one aryl-substituted olefin.

The block copolymers of this invention comprise two or more alternatingblocks, identified above. Linear block copolymers having two blocks andblock copolymers having three or more blocks are contemplated herein.

The block polymers useful according to the invention typically includeat least one block which is substantially completely saturated, whilealso including at least one block containing controlled levels ofunsaturation providing a hydrocarbon elastomer with selectivelypositioned unsaturation for subsequent functionalization. For thecopolymers prepared from two different conjugated dienes, it has beenfound that the two dienes in the copolymers hydrogenate at differentrates, permitting selective control of the placement of residualunsaturation.

The many variations in composition, molecular weight, molecular weightdistribution, relative block lengths, microstructure, branching, andT_(g) (glass transition temperature) attainable with the use of anionictechniques employed in the preparation of our polymers will be obviousto those skilled in the art.

While not wishing to limit the molecular weight range of liquidelastomers prepared according to our invention, the minimum molecularweight for these liquid polymers is at least bout 2,000, preferablyabout 2,000 to about 100,000, and most preferably about 5,000 to about35,000. The star-branched block and random copolymers of this inventionmay have substantially higher molecular weights and still retain liquidproperties. The minimum weight for solid polymers of this invention isat least about 50,000 to about 1,000,000. The block copolymers of thisinvention are functionalizable. Without wishing to be bound by anytheory of operability, it is believed that they can be functionalized ina controlled manner through the unsaturated groups on the terminal orthe interior blocks to provide dispersants and dispersant VI improvershaving almost uniform distribution of molecular weights. Thestar-branched and linear versions of the random copolymers andhomopolymers of this invention are also functionalizable.

All numerical values of molecular weight given in this specification andthe drawings are of number average molecular weight (M_(n)).

The invention will be described hereinafter in terms of the embodimentsthereof summarized above. However, it will be apparent to those skilledin the art, that the invention is not limited to these particularembodiments, but, rather, it covers all the embodiments encompassed bythe broadest scope of the description of the invention.

Copolymers From at Least Two Dissimilar Conjugated Dienes

In this embodiment of the invention, there are provided copolymers oftwo dissimilar conjugated dienes, preferably isoprene and 1,3-butadiene.The two monomers can be polymerized by anionic polymerization process ineither a block, tapered block, or random fashion.

The copolymers of this embodiment include a first conjugated dienehaving at least five (5) carbon atoms and the following formula:

wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that atleast one of R¹-R⁶ is a hydrocarbyl group, and further provided that,when polymerized, the structure of the double bond in the polymerizedconjugated diene of formula (1) has the following formula:

wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups. Inthe double bond of the polymerized conjugated diene of formula (2),R^(I), R^(II), R^(III) and R^(IV) may all be hydrocarbyl groups.

The polymers of this embodiment also include a second conjugated diene,different from the first conjugated diene, having at least four (4)carbon atoms and the following formula:

wherein R⁷-R¹² are each hydrogen or a hydrocarbyl group, provided thatthe structure of the double bond in the polymerized conjugated diene offormula (3) has the following formula:

wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group.

Following polymerization the diene copolymer of this embodiment ispreferably functionalized by a method which includes selectivelyhydrogenating the copolymer to provide a selectively hydrogenatedcopolymer, followed by functionalizing the selectively hydrogenatedcopolymer to provide a functionalized copolymer having at least onepolar functional group.

The polymers of this embodiment include a first conjugated diene offormula (1) in an amount of from about 0.5% wt. to about 30% wt., and asecond conjugated diene in an amount of from about 70% wt. to about99.5% wt. Preferably, a first conjugated diene is included in an amountof from about 1% wt. to about 25% wt., and a second conjugated diene inan amount of from about 75% to about 99% wt. More preferably, a firstconjugated diene is included in an amount of from about 5% wt. to about20% wt., and a second conjugated diene is included in an amount of fromabout 80% to about 95% wt.

The polymers of this embodiment include block copolymers having at leasttwo alternating blocks:

(I)_(x)-(B)_(y) or (B)_(y)-(I)_(x)

In this case, the polymer includes at least one block (I). The block (I)is a block of at least one polymerized conjugated diene of formula (1)as described above. These block copolymers also include at least onepolymerized block (B). The block (B) is a block of at least onepolymerized conjugated diene of formula (3) described above.

In the block copolymers of this embodiment, x is at least 1, preferablyfrom about 1 to about 600, and most preferably from about 1 to about350. The above definition of x means that each of the (I) blocks ispolymerized from at least 1, preferably about 1-600, and more preferablyabout 1-350, monomer units.

In the block copolymers of this embodiment, y is at least 25, preferablyfrom about 30 to about 4,000, more preferably from about 30 to about2,800. The above definition of y means that each of the (B) blocks ispolymerized from at least 25, preferably about 30-4,000, and morepreferably about 30-2,800, monomer units.

The block copolymer comprises about 0.5 to about 25%, preferably about 1to about 20% by wt. of the (I) blocks, and about 80 to about 99.5%,preferably about 80 to about 99% by wt. of the (B) blocks.

In any of the copolymers of this embodiment, the structures of thedouble bonds defined by formula (2) and (4) are necessary to producecopolymers which can be selectively hydrogenated in the manner describedherein, to produce the selectively hydrogenated block and randomcopolymers of this invention.

The hydrocarbyl group or groups in the formula (1) and (2) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or anyisomers thereof. Suitable hydrocarbyl groups are alkyls of 1-20 carbonatoms, alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms,aryls of 6-12 carbon atoms, alkaryls of 7-20 carbon atoms or aralkyls of7-20 carbon atoms. Examples of suitable alkyl groups are methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, methyl-decyl ordimethyl-decyl. Examples of suitable alkenyl groups are ethenyl,propenyl, butenyl, pentenyl or hexenyl. Examples of suitable cycloalkylgroups are cyclohexyl or methylcyclohexyl. Examples of suitablecycloalkenyl groups are 1-, 2-, or 3-cyclohexenyl or4-methyl-2-cyclohexenyl. Examples of suitable aryl groups are phenyl ordiphenyl. Examples of suitable alkaryl groups are 4-methyl-phenyl(p-tolyl) or p-ethyl-phenyl. Examples of suitable aralkyl groups arebenzyl or phenethyl. Suitable conjugated dienes of formula (1) used topolymerize the (I) block are isoprene, 2,3-dimethyl-butadiene,2-methyl-1,3-pentadiene, myrcene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2-phenyl-1,3-butadiene,2-phenyl-1,3-pentadiene, 3-phenyl-1,3 pentadiene,2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof, preferably isoprene, myrcene,2,3-dimethyl-butadiene, or 2-methyl-1,3-pentadiene, and most preferablyisoprene.

The hydrocarbyl group or groups in the formula (3) may or may not be thesame as those in formula (4). These hydrocarbyl groups are the same asthose described above in conjunction with the discussion of thehydrocarbyl groups of formula (1) and (2). Suitable monomers for the (B)block are 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene,1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene,3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene,1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixtures thereof,preferably 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, or1,3-hexadiene, and most preferably it is 1,3-butadiene. It is generallypreferred that each of the (B) blocks is polymerized from a singlemonomer.

The scope of this embodiment, and of any other embodiments of theinvention wherein the block (B) is used, also encompasses polymerswherein the block (B) may comprise copolymers of one or more conjugateddiene of formula (3) and controlled amounts (about 0.3 to about 30 mole%) of an aryl-substituted olefin, e.g., styrene or other suitablemonomers (such as alkylated styrene, vinyl naphthalene, or alkylatedvinyl naphthalene) incorporated for control of glass transitiontemperature (T_(g)), density, solubility parameters and refractiveindex. The aryl-substituted olefin can be incorporated randomly or as ablock. Similarly, the scope of this embodiment also encompasses polymerswherein the block (B) may be comprised of copolymers of one or moreconjugated diene of formula (3) and any other anionically polymerizablemonomer capable of polymerizing with the conjugated diene of formula(3). Similar considerations also apply in the case of the (I) block(s),which can include similar styrene/diene copolymers.

The copolymer is polymerized by anionic polymerization, discussed indetail below. As will be apparent to those skilled in the art, the blockcopolymer of this embodiment contains at least two alternating blocks,(I)-(B) or (B)-(I), referred to herein as diblocks. The block copolymerof this embodiment may contain three alternating blocks, e.g.,(I)-(B)-(I), referred to herein as triblocks or triblock units, but itmay contain an unlimited number of blocks. The functionalization of anyof these copolymers is conducted in a conventional manner and isdescribed below.

After the (I)-(B) copolymer is polymerized, it is subjected to aselective hydrogenation reaction during which the polymerized conjugateddienes of formula (3) of the copolymer are selectively hydrogenated tosuch an extent that they contain substantially none of the originalunsaturation, while the polymerized conjugated dienes of formula (1) ofthe copolymer retain a sufficient amount of their original unsaturationto permit functionalization.

Generally, for a copolymer wherein the conjugated dienes of formula (1)and (3) are polymerized to provide unsaturation of formula (2) and (4),respectively, as discussed above, the Iodine Number for the unsaturationof formula (2) after the selective hydrogenation reaction is from about20% to about 100%, preferably from about 50% to about 100%, and mostpreferably about 100%, of the Iodine Number prior to the selectivehydrogenation reaction; and for the unsaturation of formula (4) it isfrom about 0% to about 10%, preferably from about 0% to about 0.5%, andmost preferably from about 0% to about 0.2%, of the Iodine Number priorto the selective hydrogenation reaction. The Iodine Number, as is knownto those skilled in the art, is defined as the theoretical number ofgrams of iodine which will add to the unsaturation in 100 grams ofolefin and is a quantitative measure of unsaturation.

In this embodiment of the invention, although the microstructure of the(I) blocks is not critical and may consist of 1,2-, 3,4- and/or1,4-units, schematically represented below for the polyisoprene blocks,when a polar compound is used during the polymerization of the (I)block, the (I) blocks comprise primarily (at least about 50% wt.)3,4-units, the rest being primarily (less than about 50% wt.) 1,4-units;when the polar compound is not used during the polymerization of the (I)block, the (I) blocks comprise primarily (about 80% wt.) 1,4-units, therest being primarily 1,2- and 3,4-units.

The microstructure of the (B) blocks, when the predominant monomer usedto polymerize the (B) blocks is 1,3-butadiene, should be a mixture of1,4- and 1,2-units schematically shown below for the polybutadieneblocks:

since the hydrogenation of the predominantly 1,4-microstructure producesa crystalline polyethylene segment. The microstructure of the (I) and(B) blocks (as well as of the polymerized conjugated dienes of formula(1) or (3) in any polymers of this invention) is controlled in aconventional manner, e.g., by controlling the amount and nature of thepolar compounds used during the polymerization reaction, and thereaction temperature. In one particularly preferred embodiment, the (B)block contains about 50% of the 1,2- and about 50% of the1,4-microstructure. If the (B) block is poly-1,3-butadiene, thehydrogenation of the (B) segment containing from about 50% to about 60%of the 1,2-microstructure content produces an elastomeric center blockwhich is substantially an ethylene-butene-1 copolymer havingsubstantially no crystallinity. If the (B) block is polymerized from1,3-pentadiene, the microstructure is not critical.

The terms “1,2-”, “1,4-”, and “3,4-microstructure” or “units” as used inthis application refer to the products of polymerization obtained by the1,2-, 1,4- and 3,4-, respectively, mode of addition of monomer units.

We surprisingly discovered that the polymerized conjugated dienes offormula (3), e.g., the dienes employed in (B) blocks, of the polymers ofthis invention are selectively hydrogenated in our hydrogenation processmuch faster than the polymerized conjugated dienes of formula (1), e.g.,the dienes used in the (I) blocks. This is not evident from theteachings of Falk, discussed above, because Falk teaches that doublebonds of the di-substituted 1,4-polybutadiene units are hydrogenatedselectively in the presence of double bonds of the tri-substituted1,4-polyisoprene units (which hydrogenate very slowly). We surprisinglydiscovered that the di-substituted double bonds of the 1,4-polybutadieneunits are hydrogenated along with the monosubstituted double bonds ofthe 1,2-polybutadiene units, while the di-substituted double bonds ofthe 3,4-polyisoprene units are hydrogenated at a much slower rate thanthe aforementioned polybutadienes. Thus, in view of Falk's disclosure itis surprising that the di-substituted double bonds of the1,4-polybutadiene units are hydrogenated selectively in the presence ofthe di-substituted double bonds of the 3,4-polyisoprene units. This isalso surprising in view of the teachings of Hoxmeier, Published EuropeanPatent Application, Publication No. 0 315 280, who discloses that thedi-substituted double bonds of the 1,4-polybutadiene units,monosubstituted double bonds of the 1,2-polybutadiene units anddi-substituted double bonds of the 3,4-polyisoprene units arehydrogenated simultaneously at substantially the same rates. Forexample, for the block copolymers of this invention, wherein the (I)block is polyisoprene and the (B) block is polybutadiene, FourierTransform Infrared (FTIR) analysis of selectively hydrogenated blockcopolymers of the invention, such as I-B-I triblock polymers, indicatesthat the hydrogenation of the double bonds of the 1,2-polybutadieneunits proceeds most rapidly, followed by the hydrogenation of the doublebonds of the 1,4-polybutadiene units. Infrared absorptions caused bythese groups disappear prior to appreciable hydrogenation of thepolyisoprene units.

Accordingly, by controlling the amount and placement of 1,2-versus1,4-microstructure, as well as the amount and placement of polyisopreneunits, it is now possible to control the amount and placement ofunsaturation remaining in the polymers after hydrogenation. It followsthat the amount and placement of functionalization of the polymericdispersants of the invention is also controllable to an extent notpossible previously.

After the block copolymer is prepared, it is subjected to a selectivehydrogenation reaction to hydrogenate primarily the (B) block(s). Theselective hydrogenation reaction and the catalyst are described indetail below. After the hydrogenation reaction is completed, theselective hydrogenation catalyst is removed from the block copolymer,and the polymer is isolated by conventional procedures, e.g., alcoholflocculation, steam stripping of solvent, or non-aqueous solventevaporation. An antioxidant, e.g., Irganox 1076 (from Ciba-Geigy), isnormally added to the polymer solution prior to polymer isolation.

Random Copolymers

Random copolymers of this invention have controlled amounts ofunsaturation incorporated randomly in an otherwise saturated backbone.In contrast to EPDM, the level of unsaturation can be easily controlled,e.g., to produce polymers having Iodine Number of from about 5 to about100, to provide a wide variation in the degree of functionalization.

In one embodiment, the random copolymers are polymerized from the samemonomers used to polymerize the block copolymers (I)_(x)-(B)_(y),described elsewhere herein. In particular, the random copolymers may bemade by polymerizing at least one conjugated diene of formula (1) withat least one conjugated diene of formula (3), both defined above. Thisrandom copolymer contains from about 1.0% to about 40%, preferably fromabout 1.0% to about 20%, by mole of the polymerized conjugated diene offormula (1) and from about 60% to about 99%, preferably from about 80%to about 99% by mole of the polymerized conjugated diene of formula (3).Suitable conjugated dienes of formula (1) are exemplified above. Themost preferred conjugated diene of formula (1) for the copolymerizationof these random copolymers is isoprene. Suitable conjugated dienes offormula (3) are also exemplified above. 1,3-butadiene is the mostpreferred conjugated diene of formula (3) for the polymerization of therandom copolymer of this embodiment. Thus, most preferably, in thisembodiment, the random copolymer is polymerized from isoprene and1,3-butadiene, and it contains from about 1% wt. to about 20% wt. of theisoprene units and from about 80% wt. to about 99% wt. of the butadieneunits. The isoprene units have primarily (i.e., from about 50% wt. toabout 90% wt.) the 3,4-microstructure.

The random copolymers are subjected to the selective hydrogenationreaction discussed above for the block copolymers, during whichpolymerized conjugated diene units of formula (3) are substantiallycompletely hydrogenated, while the conjugated diene units of formula (1)are hydrogenated to a substantially lesser extent, i.e., to such anextent that they retain a sufficient amount of their originalunsaturation to functionalize the copolymer, thereby producingdispersants and dispersant VI improvers having random unsaturationproportional to the unsaturation in the polymerized dienes of formula(1). For example, for random copolymer polymerized from a diene offormula (1) and a different diene of formula (3), the Iodine Numberbefore selective hydrogenation for the polymer is about 450. Afterselective hydrogenation, the Iodine Number for the polymer is from about10 to about 50, with most of the unsaturation being contributed by thediene of formula (1).

The hydrogenated polymers are functionalized in the same manner as setforth for block copolymers.

Star-Branched Polymers

The invention is also directed to star-branched block and randompolymers. The star-branched block polymers are made from any combinationof blocks (I) and (B), defined above.

The star-branched (I)-(B) block polymers comprise from about 0.5% wt. toabout 25% wt., preferably from about 1% wt. to about 20% wt., of the (I)blocks, and from about 75% wt. to about 99.5% wt., preferably from about80% wt. to about 99% wt., of the (B) blocks.

The star-branched block polymers are selectively hydrogenated in theselective hydrogenation process of this invention to such an extent thatblocks (B) contain substantially none of the original unsaturation,while each of the blocks (I) respectively, retains a sufficient amountof the original unsaturation of the conjugated dienes present in theseblocks to functionalize the star-branched block polymers. Thus, for theI-(B) star-branched block polymer, after the selective hydrogenationreaction, the Iodine Number for the (I) blocks is from about 10% toabout 100%, preferably from about 25% to about 100%, more preferablyfrom about 50% to about 100%, and most preferably about 100%, of theIodine Number prior to the selective hydrogenation reaction; and for the(B) blocks it is from about 0% to about 10%, preferably from about 0% toabout 0.5%, of the Iodine Number prior to the selective hydrogenationreaction.

The star-branched random polymers are made from any combination of atleast one diene of formula (1) and at least one diene of formula (3),different from the diene of formula (1), or from any combination of atleast one aryl-substituted olefin and at least one diene of formula (1)or (3), all of which are the same as those discussed above. Thestar-branched random polymers of the dienes of formula (1) and (3),which must be different from each other, comprise from about 0.5% wt. toabout 25% wt., preferably from about 1% wt. to about 20% wt., of thediene of formula (1), and from about 75% wt. to about 99.5% wt.,preferably from about 80% wt. to about 99% wt., of the diene of formula(3). The star-branched random polymers of the aryl-substituted olefinand the diene of formula (1) or (3) comprise from about 0.5% wt. toabout 50% wt., preferably from about 1% wt. to about 25% wt., of thearyl-substituted olefin, and from about 50% wt. to about 99.5% wt.,preferably from about 75% wt. to about 99% wt., of the diene of formula(1) or (3).

The star-branched random diene polymers are also selectivelyhydrogenated in the selective hydrogenation process of this invention tosuch an extent that the polymerized dienes of formula (3) containsubstantially none of the original unsaturation, while the polymerizeddienes of formula (1) retain a sufficient amount of the originalunsaturation to functionalize the star-branched random polymers. Thus,for the star-branched random polymer of the conjugated diene of formula(1) and a different diene of formula (3), both identified above, theIodine Number for the polymerized diene of formula (1), after theselective hydrogenation reaction, is from about 10% to about 100%,preferably from about 25% to about 100%, more preferably from about 50%to about 100%, and most preferably about 100%, of the Iodine Numberprior to the selective hydrogenation reaction; and for the polymerizeddiene of formula (3) it is from about 0% to about 10%, preferably fromabout 0% to about 0.5%, of the Iodine Number prior to the selectivehydrogenation reaction.

Polymerization Reaction

The polymers of this invention are polymerized by any knownpolymerization processes, preferably by an anionic polymerizationprocess. Anionic polymerization is well known in the art and it isutilized in the production of a variety of commercial polymers. Anexcellent comprehensive review of the anionic polymerization processesappears in the text Advances in Polymer Science 56, AnionicPolymerization, pp. 1-90, Springer-Verlag, Berlin, Heidelberg, N.Y.,Tokyo 1984 in a monograph entitled Anionic Polymerization of Non-polarMonomers Involving Lithium, by R. N. Young, R. P. Quirk and L. J.Fetters, incorporated herein by reference. The anionic polymerizationprocess is conducted in the presence of a suitable anionic catalyst(also known as an initiator), such as n-butyl-lithium,sec-butyl-lithium, t-butyl-lithium, sodium naphthalide or, cumylpotassium. The amount of the catalyst and the amount of the monomer inthe polymerization reaction dictate the molecular weight of the polymer.The polymerization reaction is conducted in solution using an inertsolvent as the polymerization medium, e.g., aliphatic hydrocarbons, suchas hexane, cyclohexane, or heptane, or aromatic solvents, such asbenzene or toluene. In certain instances, inert polar solvents, such astetrahydrofuran, can be used alone as a solvent, or in a mixture with ahydrocarbon solvent.

The polymerization process will be exemplified below for thepolymerization of one of the embodiments of the invention, e.g., atriblock of polyisoprene-polybutadiene-polyisoprene. However, it will beapparent to those skilled in the art that the same process principlescan be used for the polymerization of all polymers of the invention.

The process, when using a lithium-based catalyst, comprises forming asolution of the isoprene monomer in an inert hydrocarbon solvent, suchas cyclohexane, modified by the presence therein of one or more polarcompounds selected from the group consisting of ethers, thioethers, andtertiary amines, e.g., tetrahydrofuran. The polar compounds arenecessary to control the microstructure of the butadiene center block,i.e., the content of the 1,2-structure thereof. The higher the contentof the polar compounds, the higher will be the content of the1,2-structure in these blocks. Since the presence of the polar compoundis not essential in the formation of the first polymer block with manyinitiators unless a high 3,4-structure content of the first block isdesired, it is not necessary to introduce the polar compound at thisstage, since it may be introduced just prior to or together with theaddition of the butadiene in the second polymerization stage. Examplesof polar compounds which may be used are dimethyl ether, diethyl ether,ethyl methyl ether, ethyl propyl ether, dioxane, diphenyl ether,dipropyl ether, tripropyl amine, tributyl amine, trimethyl amine,triethyl amine, and N-N-N′-N′-tetramethyl ethylene diamine. Mixtures ofthe polar compounds may also be used. The amount of the polar compounddepends on the type of the polar compound and the polymerizationconditions as will be apparent to those skilled in the art. The effectof polar compounds on the polybutadiene microstructure is detailed inAntkowiak et al. The polar compounds also accelerate the rate ofpolymerization. If monomers other than 1,3-butadiene, e.g., pentadiene,are used to polymerize the central blocks (B), polar compounds are notnecessary to control the microstructure because such monomers willinherently produce polymers which do not possess crystallinity afterhydrogenation.

When the alkyl lithium-based initiator, a polar compound and an isoprenemonomer are combined in an inert solvent, polymerization of the isopreneproceeds to produce the first terminal block whose molecular weight isdetermined by the ratio of the isoprene to the initiator. The livingpolyisoprenyl anion formed in this first step is utilized as thecatalyst for further polymerization. At this time, butadiene monomer isintroduced into the system and block polymerization of the second blockproceeds, the presence of the polar compound now influencing the desireddegree of branching (1,2-structure) in the polybutadiene block. Theresulting product is a living diblock polymer having a terminal anionand a lithium counterion. The living diblock polymer serves as acatalyst for the growth of the final isoprene block, formed whenisoprene monomer is again added to the reaction vessel to produce thefinal polymer block, resulting in the formation of the I-B-I triblock.Upon completion of polymerization, the living anion, now present at theterminus of the triblock, is destroyed by the addition of a protondonor, such as methyl alcohol or acetic acid. The polymerizationreaction is usually conducted at a temperature of between about 0° C.and about 100° C., although higher temperatures can be used. Control ofa chosen reaction temperature is desirable since it can influence theeffectiveness of the polar compound additive in controlling the polymermicrostructure. The reaction temperature can be, for example, from about50° C. to about 80° C. The reaction pressure is not critical and variesfrom about atmospheric to about 100 psig.

If the polar compounds are utilized prior to the polymerization of thefirst (I) segment, (I) blocks with high 3,4-unit content are formed. Ifpolar compounds are added after the initial (I) segment is prepared, thefirst (I) segment will possess a high percentage of 1,4-microstructure(which is tri-substituted), and the second (I) segment will have a highpercentage of 3,4-microstructure.

The production of triblock polymers having a high 1,4-unit content onboth of the terminal (I) blocks is also possible by the use of couplingtechniques illustrated below for apolyisoprene-polybutadiene-polyisoprene block copolymer:${\text{ISOPRENE}\overset{RLi}{>}{1\text{,}4\text{-}{POLYISOPRENE}}}\underset{\text{BUTADIENE}}{\overset{\text{POLAR~~~COMPOUND}\quad}{\rightarrow}}{{{1\text{,}4\text{-}{POLYISOPRENE}\text{-}{POLYBUTADIENE}}\overset{\text{COUPLING~~AGENT}\quad}{\rightarrow}\quad {\text{1,4-POLYISOPRENE-POLYBUTADIENE-1,4-POLYISOPRENE}}}}$

The substitution of myrcene for the isoprene during the polymerizationof the (I) blocks insures the incorporation of a high proportion oftri-substituted double bonds, even in the presence of polar compoundssince myrcene contains a pendant tri-substituted double bond which isnot involved in the polymerization process. In a coupling process,similar to that described above, block polymers containing polyisopreneend blocks (or any other polymerized monomer suitable for use in the (I)block) having a high 3,4-microstructure content can be obtained byadding the polar compound prior to the isoprene (or another monomer)polymerization.

The use of the coupling technique for the production of triblockpolymers reduces the reaction time necessary for the completion ofpolymerization, as compared to sequential addition of isoprene, followedby butadiene, followed by isoprene. Such coupling techniques are wellknown and utilize coupling agents such as esters, CO₂, iodine,dihaloalkanes, silicon tetrachloride, divinyl benzene, alkyltrichlorosilanes and dialkyl dichlorosilanes. The use of tri- ortetra-functional coupling agents, such as alkyl trichlorosilanes orsilicon tetrachloride, permits the formation of macromolecules having 1-or 2-main chain branches, respectively. The addition of divinyl benzeneas a coupling agent has been documented to produce molecules having upto 20 or more separately joined segments.

The use of some of the coupling agents provides a convenient means ofproducing star-branched block and random polymers. The star-branchedblock polymers are made from any combination of blocks (I) and (B),defined above. The star-branched random polymers are made from anycombination of at least one diene of formula (1) and at least one dieneof formula (3), different from the diene of formula (1), or from atleast one aryl-substituted olefin, at least one diene of formula (1) andat least one diene of formula (3), different from the diene of formula(1). The molecular weight of the star-branched block and randomcopolymers will depend on the number of branches in each such copolymer,as will be apparent to those skilled in the art. Suitable couplingagents and reactions are disclosed in the following references which areincorporated herein by reference: U.S. Pat. Nos. 3,949,020; 3,594,452;3,598,887; 3,465,065; 3,078,254; 3,766,301; 3,632,682; 3,668,279; andGreat Britain patent Nos. 1,014,999; 1,074,276; 1,121,978.

Selective Hydrogenation

Following polymerization, selective hydrogenation of the polymer may beaccomplished using techniques similar to those known in the art. Apreferred method and catalyst are described in U.S. Pat. No. 5,187,236,the disclosure of which is incorporated herein by reference. Theprocedure and catalyst are described in greater detail below. Ingeneral, however, the previously described polymers can be contactedwith hydrogen and a hydrogenation catalyst synthesized from a transitionmetal compound, typically nickel or cobalt, and an organometallicreducing agent, e.g., triethylaluminum. The hydrogenation proceeds attemperatures typically not in excess of about 40° C. and at pressures offrom about 30 psi to about 200 psi. Generally, the polymers arehydrogenated such that substantially all of the unsaturation in formula(4) is removed, while much of that from formula (2) is retained.

The selective hydrogenation reaction will also be described below usinga triblock of polyisoprene-polybutadiene-polyisoprene as an example.However, it will be apparent to those skilled in the art that anypolymers of this invention can be selectively hydrogenated in the samemanner.

In Example II below, the block copolymer is selectively hydrogenated tosaturate the middle (polybutadiene) block. The method of selectivelyhydrogenating the polybutadiene block is similar to that of Falk,Coordination Catalysts for the Selective Hydrogenation of PolymericUnsaturation, Journal of Polymer Science: Part A-1, 9:2617-23 (1971),but it is conducted with a novel hydrogenation catalyst and process usedherein. Any other known selective hydrogenation methods may also beused, as will be apparent to those skilled in the art, but it ispreferred to use the method described herein. In summary, the selectivehydrogenation method preferably used herein comprises contacting thepreviously-prepared block copolymer with hydrogen in the presence of thenovel catalyst composition.

The novel hydrogenation catalyst composition and hydrogenation processare described in detail in previously cited application Ser. No.07/466,136. The hydrogenation catalyst composition is synthesized fromat least one transition metal compound and an organometallic reducingagent. Suitable transition metal compounds are compounds of metals ofGroup IVb, Vb, VIb or VIII, preferably IVb or VIII of the Periodic Tableof the Elements, published in Lange's Handbook of Chemistry, 13th Ed.,McGraw-Hill Book Company, New York (1985) (John A. Dean, ed.).Non-limiting examples of such compounds are metal halides, e.g.,titanium tetrachloride, vanadium tetrachloride; vanadium oxytrichloride,titanium and vanadium alkoxides, wherein the alkoxide moiety has abranched or unbranched alkyl radical of 1 to about 20 carbon atoms,preferably 1 to about 6 carbon atoms. Preferred transition metalcompounds are metal carboxylates or alkoxides of Group IVb or VIII ofthe Periodic Table of the Elements, such as nickel (II)2-ethylhexanoate, titanium isopropoxide, cobalt (II) octoate, nickel(II) phenoxide and ferric acetylacetonate.

The organometallic reducing agent is any one or a combination of any ofthe materials commonly employed to activate Ziegler-Natta olefinpolymerization catalyst components containing at least one compound ofthe elements of Groups Ia, IIa, IIb, IIIa, or IVa of the Periodic Tableof the Elements. Examples of such reducing agents are metal alkyls,metal hydrides, alkyl metal hydrides, alkyl metal halides, and alkylmetal alkoxides, such as alkyllithium compounds, dialkylzinc compounds,trialkylboron compounds, trialkylaliminum compounds, alkylaluminumhalides and hydrides, and tetraalkylgermanium compounds. Mixtures of thereducing agents may also be employed. Specific examples of usefulreducing agents include n-butyllithium, diethylzinc, di-n-propylzinc,triethylboron, diethylaluminumethoxide, triethylaluminum,trimethylaluminum, triisobutylaluminum, tri-n-hexylaluminum,ethylaluminum dichloride, dibromide, and dihydride, isobutyl aluminumdichloride, dibromide, and dihydride, diethylaluminum chloride, bromide,and hydride, di-n-propylaluminum chloride, bromide, and hydride,diisobutylaluminum chloride, bromide and hydride, tetramethylgermanium,and tetraethylgermanium. Organometallic reducing agents which arepreferred are Group IIIa metal alkyls and dialkyl metal halides having 1to about 20 carbon atoms per alkyl radical. More preferably, thereducing agent is a trialkylaluminum compound having 1 to about 6 carbonatoms per alkyl radical. Other reducing agents which can be used hereinare disclosed in Stevens et al., U.S. Pat. No. 3,787,384, column 4, line45 to column 5, line 12 and in Strobel et al., U.S. Pat. No. 4,148,754,column 4, line 56 to column 5, line 59, the entire contents of both ofwhich are incorporated herein by reference. Particularly preferredreducing agents are metal alkyl or hydride derivatives of a metalselected from Groups Ia, IIa and IIIa of the Periodic Table of theElements, such as n-butyl lithium, sec-butyl lithium, n-hexyl lithium,phenyl-lithium, triethylaluminum, tri-isobutylaluminum,trimethylaluminum, diethylaluminum hydride and dibutylmagnesium.

The molar ratio of the metal derived from the reducing agent to themetal derived from the transition metal compound will vary for theselected combinations of the reducing agent and the transition metalcompound, but in general it is about 1:1 to about 12:1, preferably about1.5:1 to about 8:1, more preferably about 2:1 to about 7:1, and mostpreferably about 2.5:1 to about 6:1. It will be apparent to thoseskilled in the art that the optimal ratios will vary depending upon thetransition metal and the organometallic agent used, e.g., for thetrialkylaluminum/nickel(II) systems, the preferred aluminum:nickel molarratio is about 2.5:1 to about 4:1, for the trialkylaluminum/cobalt(II)systems, the preferred aluminum:cobalt molar ratio is about 3:1 to about4:1, and for the trialkylaluminum/titanium(IV) alkoxides systems, thepreferred aluminum:titanium molar ratio is about 3:1 to about 6:1.

The mode of addition and the ratio of the reducing agent to thetransition metal compound are important in the production of the novelhydrogenation catalyst having superior selectivity, efficiency andstability, as compared to prior art catalytic systems. During thesynthesis of the catalysts it is preferred to maintain the molar ratioof the reactants used to synthesize the catalyst substantially constant.This can be done either by the addition of the reducing agent, asrapidly as possible, to a solution of the transition metal compound, orby a substantially simultaneous addition of the separate streams of thereducing agent and the transition metal compound to a catalyst synthesisvessel in such a manner that the selected molar ratios of the metal ofthe reducing agent to the metal of the transition metal compound aremaintained substantially constant throughout substantially the entiretime of addition of the two compounds. The time required for theaddition must be such that excessive pressure and heat build-up areavoided, i.e., the temperature should not exceed about 80° C. and thepressure should not exceed the safe pressure limit of the catalystsynthesis vessel.

In a preferred embodiment, the reducing agent and the transition metalcompound are added substantially simultaneously to the catalystsynthesis vessel in such a manner that the selected molar ratio of thereducing agent to the transition metal compound is maintainedsubstantially constant during substantially the entire time of theaddition of the two compounds. This preferred embodiment permits thecontrol of the exothermic reaction so that the heat build-up is notexcessive, and the rate of gas production during the catalyst synthesisis also non excessive—accordingly, the gas build-up is relatively slow.In this embodiment, carried out with or without a solvent diluent, therate of addition of the catalyst components is adjusted to maintain thesynthesis reaction temperature at or below about 80° C., which promotesthe formation of the selective hydrogenation catalyst. Furthermore, theselected molar ratios of the metal of the reducing agent to the metal ofthe transition metal compound are maintained substantially constantthroughout the entire duration of the catalyst preparation when thesimultaneous mixing technique of this embodiment is employed.

In another embodiment, the catalyst is formed by the addition of thereducing agent to the transition metal compound. In this embodiment, thetiming and the order of addition of the two reactants is important toobtain the hydrogenation catalyst having superior selectivity,efficiency and stability. Thus, in this embodiment, it is important toadd the reducing agent to the transition metal compound in that order inas short a time period as practically possible. In this embodiment, thetime allotted for the addition of the reducing agent to the transitionmetal compound is critical for the production of the novel catalyst. Theterm “as short a time period as practically possible” means that thetime of addition is as rapid as possible, such that the reactiontemperature is not higher than about 80° C. and the reaction pressuredoes not exceed the safe pressure limit of the catalyst synthesisvessel. As will be apparent to those skilled in the art, that time willvary for each synthesis and will depend on such factors as the types ofthe reducing agents, the transition metal compounds and the solventsused in the synthesis, as well as the relative amounts thereof, and thetype of the catalyst synthesis vessel used. For purposes ofillustration, a solution of about 15 mL of triethylaluminum in hexaneshould be added to a solution of nickel(II) octoate in mineral spiritsin about 10-30 seconds. Generally, the addition of the reducing agent tothe transition metal compound should be carried out in about 5 seconds(sec) to about 5 minutes (min), depending on the quantities of thereagents used. If the time period during which the reducing agent isadded to the transition metal compound is prolonged, e.g., more than 15minutes, the synthesized catalyst is less selective, less stable, andmay be heterogeneous.

In the embodiment wherein the reducing agent is added as rapidly aspossible to the transition metal compound, it is also important to addthe reducing agent to the transition metal compound in theaforementioned sequence to obtain the novel catalyst. The reversal ofthe addition sequence, i.e., the addition of the transition metalcompound to the reducing agent, or the respective solutions thereof, isdetrimental to the stability, selectivity, activity, and homogeneity ofthe catalyst and is, therefore, undesirable.

In all embodiments of the hydrogenation catalyst synthesis, it ispreferred to use solutions of the reducing agent and the transitionmetal compound in suitable solvents, such as hydrocarbon solvents, e.g.,cyclohexane, hexane, pentane, heptane, benzene, toluene, or mineraloils. The solvents used to prepare the solutions of the reducing agentand of the transition metal compound may be the same or different, butif they are different, they must be compatible with each other so thatthe solutions of the reducing agent and the transition metal compoundare fully soluble in each other.

The hydrogenation process comprises contacting the unsaturated polymerto be hydrogenated with an amount of the catalyst solution containingabout 0.1 to about 0.5, preferably about 0.2 to about 0.3 mole percentof the transition metal based on moles of the polymer unsaturation. Thehydrogen partial pressure is generally from about 5 psig to aboutseveral hundred psig, but preferably it is from about 10 psig to about100 psig. The temperature of the hydrogenation reaction mixture isgenerally from about 0° C. to about 150° C., preferably from about 25°C. to about 80° C., more preferably from about 30° C. to about 60° C.,since higher temperatures may lead to catalyst deactivation. The lengthof the hydrogenation reaction may be as short as 30 minutes and, as willbe apparent to those skilled in the art, depends to a great extent onthe actual reaction conditions employed. The hydrogenation process maybe monitored by any conventional means, e.g., infra-red spectroscopy,hydrogen flow rate, total hydrogen consumption, or any combinationthereof.

Upon completion of the hydrogenation process, unreacted hydrogen iseither vented or consumed by the introduction of the appropriate amountof an unsaturated material, such as 1-hexene, which is converted to aninert hydrocarbon, e.g., hexane. Subsequently, the catalyst is removedfrom the resulting polymer solution by any suitable means, selecteddepending on the particular process and polymer. For a low molecularweight material, for example, catalyst residue removal may consist of atreatment of the solution with an oxidant, such as air, and subsequenttreatment with ammonia and optionally methanol in amounts equal to themolar amount of the metals (i.e., the sum of the transition metal andthe metal of the reducing agent) present in the hydrogenation catalystto yield the catalyst residues as a filterable precipitate, which isfiltered off. The solvent may then be removed by any conventionalmethods, such as vacuum stripping, to yield the product polymer as aclear, colorless fluid.

Alternatively, and in a preferred embodiment, upon completion of thehydrogenation reaction, the mixture is treated with ammonia in the molaramount about equal to that of the metals (i.e., the sum of thetransition metal and the metal of the reducing agent) and aqueoushydrogen peroxide, in the molar amount equal to about one half to aboutone, preferably one half, of the amount of the metals. Other levels ofthe ammonia and peroxide are also operative, but those specified aboveare particularly preferred. In this method, a precipitate forms, whichmay be filtered off as described above.

In yet another alternative method, the catalyst may be removed byextraction with an aqueous mineral acid, such as sulfuric, phosphoric,or hydrochloric acid, followed by washing with distilled water. A smallamount of a material commonly used as an aid in removing transitionmetal-based catalysts, such as a commercially available high molecularweight diamine, e.g., Jeffamine D-2000 from Huntsman, may be added toaid in phase separation and catalyst removal during the extractions. Theresultant polymer solution is then dried over a drying agent, such asmagnesium sulfate, separated from the drying agent and the solvent isthen separated by any conventional methods, such as vacuum stripping, toyield a polymer as a clear fluid. Other methods of polymer isolation,such as steam or alcohol flocculation, may be employed depending uponthe hydrogenated polymer properties.

After hydrogenation and purification is complete, the polymer can befunctionalized and used in the lubricant compositions of the invention:the liquids will serve as dispersants and the solids as dispersant VIimprovers.

Functionalization of the Polymers

The unsaturated terminal blocks of the block polymers of this inventioncan be chemically modified or functionalized to provide benefits whichenhance the dispersancy and viscosity improving qualities of thematerials of the invention. Such benefits may be obtained throughmethods similar to those employed for the modification of existingcommercial materials, such as polyisobutylene or EPDM.

Following the selective hydrogenation step, the remaining sites ofunsaturation may be chemically modified. Such methods include reactingthe unsaturated groups in the polymer with any of various reagents toproduce functional groups, such as halogen, hydroxyl, epoxy, sulfonicacid, mercapto, acrylate or carboxyl groups. Functionalization methodsare well known in the art.

A preferred chemical modification method involves reaction of thepolymer with an unsaturated carboxylic acid and/or derivatives, such asacrylic acid, maleic acid, fumaric acid, maleic anhydride, methacrylicacid, esters of these acids, and the like. Most preferably, maleicanhydride is used for the chemical modification of unsaturation.Numerous methods are known for the chemical modification ofpolyisobutylene and EPDM via the ene reaction. Methods are also knownfor the reaction of maleic anhydride with EPDM via a radical reaction inthe presence of a radical initiator. These methods can be adapted toincorporate the unsaturated carboxylic acid derivatives into thepolymeric dispersants of the invention.

Subsequent to the acylation reaction (or other suitable chemicalmodifications as outlined above), the chemically modified polymers maybe reacted with a Lewis base, such as a monoamine, a polyamine, apolyhydroxy compound, a reactive polyether, or a combination thereof.Amines which are useful for this modification reaction are characterizedby the presence of at least one primary (i.e., H₂N—) or secondary (i.e.,HN═) amino group. The monoamines and polyamines can be aliphatic amines,cycloaliphatic amines, heterocyclic amines, aromatic amines, orhydroxyamines. Preferably, the polyamines contain only one primary orsecondary amine, with the remaining amines being tertiary (i.e., —N═) oraromatic amines. The amination can be accomplished by heating the maleicanhydride-modified diene polymer to about 150° C. in the presence of theamine, followed by stripping off the water. A useful monoamine isethanol amine. Useful polyamines include aminopropylmorpholine andtetraethylenepentamine. Useful polyhydroxy compounds include ethyleneglycol and pentaerythritol. Useful reactive polyethers includepolyethers which contain hydroxy or amino groups which will react withthe modified polymer, such as polyethylene glycol monoalcohol. Inaddition, when the modified polymers react with an aromatic polyamine,the resultant dispersant has improved antioxidant properties.

In a preferred functionalization of diene copolymers, the selectivelyhydrogenated copolymer is functionalized with functional groups selectedfrom among halogens IV, epoxies, sulfonic acids, mercapto acid and/orderivatives and carboxylic acid derivatives, and subsequently modifiedfurther by reacting with a monoamine, a polyamine, a polyhydroxycompound, a reactive polyether, or a combination thereof.

The ene reaction of maleic anhydride with materials of the invention canbe performed on neat polymers or solutions of the polymers in lightmineral oil or polyalphaolefin at temperatures of from about 150° C. toabout 250° C., typically under an inert atmosphere. Such modification ofthe polymers of any embodiments of our invention occurs readily, sincethe residual isoprene unsaturation, primarily of the 3,4-type,illustrated above, is known to be more reactive with maleic anhydridethan are the internal bonds found in EPDM.

In addition, the selectively hydrogenated polymer may be functionalizedby other methods which enhance the dispersancy, including but notlimited to: grafting of heteroatom-containing olefins; formation ofMannich base condensates at the sites of unsaturation;hydroformylation/reductive amination; addition of nitrosamines ornitrosophenols; lithiation followed by reaction with electrophiliccompounds capable of displacement or addition reactions to providecarboxy, nitrilo, or amino groups; 1,3-dipolar addition of nitrileoxides, nitrones, and the like; light catalyzed cycloaddition ofactivated olefins; and light catalyzed insertion reactions.

Grafting of heteroatom-containing olefins may be accomplished byreacting the polymer with a vinyl monomer in the presence of a freeradical initiator, such as t-butylperoxybenzoate, to directly form adispersant molecule. Nitrogen and/or oxygen-containing vinyl monomers,such as vinyl imidazole and maleic anhydride, may be used. The number ofvinyl monomers appended to the polymer in this fashion can be from 1 to20 or more per 10,000 molecular weight.

Suitable vinyl monomers are disclosed in U.S. Pat. Nos. 5,663,126;5,140,075; 5,128,086; 4,146,489; 4,092,255; and 4,810754, incorporatedherein by reference.

Suitable free radical initiators are disclosed in U.S. Pat. Nos.5,663,126 and 4,146,489, incorporated herein by reference.

Any conventional grafting method may be used. For example, the graftingmay be performed by dissolving the polymer in a solvent, preferably ahydrocarbon solvent, adding a free radical initiator and a nitrogenand/or oxygen-containing vinyl monomer. The mixture is then heated toobtain a grafted polymer. The grafted polymer may be isolated byconventional methods. For example, the graft copolymer may be convertedto a concentrate by evaporative distillation of solvent, non-reactedvinyl monomer, and reaction by-products. For ease of handling, a mineraloil diluent may be added before or after the evaporative procedure.

The grafted polymer may be further reacted with an amine, preferablycontaining at least one —NH group. Suitable amines include monoamines,polyamines, amino alcohols, amino acids or derivatives thereof, andamino terminated polyethers.

The selectively hydrogenated polymer may also be functionalized by aMannich base condensation reaction or chemical modification followed bya Mannich base condensation reaction. The polymer is reacted with aphenol to provide a hydroxy aromatic functionalized polymer which issubsequently reacted with an aldehyde or aldehyde precursor and at leastone amino or polyamino compound having at least one —NH group to form adispersant molecule. The number of phenolic groups (Mannich condensates)per molecule can be from 1 to 20 or more per 10,000 molecular weight.

Useful amines in the preparation of the Mannich condensate dispersantsof this invention include monoamines, polyamines, amino alcohols, aminoacids or derivatives thereof, and amino terminated polyethers with theproviso that the amine has at least one —NH group.

Suitable aldehydes include C₁ to C₁₀ linear, cyclic or branchedaldehydes.

Mannich base condensation reactions are described in U.S. Pat. Nos.3,413,347; 3,697,574; 3,634,515; 3,649,229; 3,442,808; 3,798,165;3,539,633; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 5,102,566; and5,663,130, incorporated herein by reference.

Alternatively, the selectively hydrogenated polymer may befunctionalized by aminomethylation or hydroformylation followed byreductive amination. The polymer is reacted with carbon monoxide andhydrogen, in the presence of a transition metal catalyst to providecarbonyl derivatives of the polymer. The functionalized polymer issubsequently modified by reductive amination. Useful amines include, butare not limited to, monoamines, polyamines, amino alcohols, amino acidsor derivatives thereof, and amino terminated polyethers with the provisothat the amine has at least one NH group. The number of suitablereaction sites per molecule can be from 1 to 20 or more per 10,000molecular weight.

Aminomethylation and hydroformylation followed by reductive aminationare described in U.S. Pat. Nos. 3,311,598; 3,438,757; 4,832,702; and5,691,422, incorporated herein by reference.

The above description illustrates only some of the potentially valuablechemical modification of the polymers of this invention. The polymers ofthis invention provide a means for a wide variety of chemicalmodifications at selected sites in the polymer, e.g., at select ends, inthe middle, or randomly, thereby presenting the opportunity to preparematerials previously impossible because of the lack of availability ofsuch polymers. Some examples of well known chemical reactions which canbe performed on polymers of this invention are found in E. M. Fettes,“Chemical Reactions of Polymers”, High Polymers, Vol. 19, John Wiley,New York, (1964), incorporated herein by reference.

Post Treatment of the Polymers

Post treatment compositions of this invention include those formed bycontacting the dispersants of this invention with one or morepost-treating agents to give improved properties to finished lubricants.Such improved properties include enhanced performance in hightemperature oxidation tests and in deposit and wear related full scaleengine tests.

Suitable post-treating agents include boronating agents; phosphorylatingagents; alkaline earth metal oxidating, sulfonating and carbonatingagents; and IB and IIB metal oxidating, sulfating and sulfonatingagents.

Suitable boronating agents or boron-containing compounds include boronacids, particularly boric acid or metaboric acid, boron oxide, boronoxide hydrate, boron esters, boron salts, particularly an ammoniumborate, and boron halides.

Suitable phosphorylating agents include an inorganic acid of phosphorus,such as phosphorous acid and phosphoric acid an anhydride thereof, apartial or complete sulfur analog thereof and an organic acid phosphate,such as 2-ethylhexyl acid phosphate.

Suitable alkaline earth oxidating, sulfonating and carbonating agentsinclude calcium oxide, calcium sulfonate, calcium carbonate, bariumoxide, barium sulfonate and barium carbonate.

Suitable IB and IIB metal oxidating, sulfating and sulfonating agentsinclude zinc sulfate, zinc oxide, zinc sulfonate and cuprous oxide.

Post-treating agents and methods by which they can be employed ineffecting post treatment of ashless dispersants are disclosed in U.S.Pat. Nos. 5,464,549 and 4,234,435 incorporated herein by reference.

Dispersant and VI-Improving Applications

The polymers of the invention, whether block copolymers, tapered blockcopolymers, branched and star branched polymers, or random copolymers,have been found to have an unexpected capacity to modify the dispersancyand/or viscometric properties of fluids, such as mineral and syntheticoil lubricants and normally liquid fuels. Accordingly, it is within thescope of the invention that the dispersant polymers of the invention beemployed in dispersant substances which can be added to fluids to modifythe dispersancy and/or viscometric properties of the fluids. Theinvention, thus, also includes a method of modifying or improving thedispersancy and/or viscometric properties of a fluid by admixing withthe fluid a sufficient amount of a dispersant substance of the inventionso as to obtain or provide a modified or improved fluid having modifiedor improved dispersancy and/or viscometric properties. Moreover, theinvention also includes dispersant-modified or dispersant-improvedfluids to which have been added a dispersant substance of the inventionso as to modify the dispersancy and/or viscometric properties of thefluid.

The improvement of viscometric properties includes any one or more ofthe properties of fluids which are related to viscosity. The dispersantVI improvers of the invention specifically improve the viscosity indexof such fluids. Viscosity index is a property characterizing therelationship between the viscosity of a fluid and temperature.Improvement in viscosity index is characterized by a decrease in therate of change of viscosity per unit of temperature change. Typicalproperties which are modified or improved by the dispersant VI improversof the invention include relative thickening power (RTP), borderlinepumpability, permanent shear stability (DIN), temporary shear stabilityat low temperatures (CCS), and temporary shear stability at hightemperatures (HTHS). Each of these properties can be determined orcharacterized by conventional methods.

The polymers of the invention may be employed as dispersants and/ordispersant VI improvers in a variety of lubricant fluids. Typically,such fluid is a mineral oil such as a mineral oil lubricant system,e.g., motor oils, automatic transmission fluids, tractor hydraulicfluids, gear oils, aviation oils, and the like. Other suitableapplications include normally liquid fuels. The lubricant or fuel may benaturally occurring or synthetic, or a combination thereof. Natural oilsinclude mineral oils obtained from petroleum, including distillate andresidual lubricating oils, and the like. Synthetic oils can includesynthetic hydrocarbon fluids e.g. PAOs, liquid esters, fluorocarbons,polyethers, polysilicones, and the like. The dispersants can be added toa lubricant or fuel formulation in any suitable and effective amount tomodify the dispersancy and/or viscometric properties of the formulation.An exemplary broad range is from about 0.001% wt. to about 20% wt.,preferably from about 0.1% wt. to about 10% wt., more preferably fromabout 0.5% wt. to about 7% wt., of the formulation.

The polymers of the invention can be supplied neat or as an oilconcentrate for ease of handling. Typically, such dispersantconcentrates include a polymer of the invention in an amount of fromabout 5% wt. to about 90% wt., preferably from about 10% wt. to about70% wt., of the concentrate.

In addition to the polymers described in this invention, the dispersantformulations and the fluid formulations can further include one or moreadditional additives known to those skilled in the art. Such additivesinclude, for example, antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, VI improvers,anti-foam agents, corrosion and rust inhibitors, etc. Indeed, it isamong the advantages of the compositions of the invention that they areunusually efficient modifiers of dispersancy and/or viscometricproperties, such that in many cases significantly less of theseadditives need be added to achieve a desired combination of fluidproperties.

EXAMPLES

The following examples are intended to assist in a further understandingof the invention. The particular materials and conditions employed areintended to be further illustrative of the invention and are notlimiting upon the reasonable scope thereof.

In all of the following examples, the experimental polymerization andfunctionalization work was performed with dried reactors and equipmentand under strictly anaerobic conditions. Extreme care must be used toexclude air, moisture and other impurities capable of interfering withthe delicate chemical balance involved in the synthesis of the polymersof this invention, as will be apparent to those skilled in the art.

Example I Preparation of Dispersant Precursor Backbones

Eleven hundred milliliters of purified pentane is introduced under anitrogen atmosphere into a two quart glass-bowled pressure reactor. Thereactor is equipped with an air driven stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with a valve, a syringe injection port containing a Vitonrubber gasket, and a blow-out disk (200 psi). Two milliliters of a 0.1 Mdipyridyl in cyclohexane solution is injected into the reactor alongwith 2.5 mL of anhydrous tetrahydrofuran. Purified isoprene (33.4 mL,334 mmol) is injected into the reactor followed by purified styrene(8.33 mL, 72.8 mmol). The temperature of the reactor and its contents israised to 50° C. The solution is then titrated by the addition of 1.6Mbutyllithium until a persistent red color is obtained. Following this,9.48 mL of 1.6M butyllithium is injected into the reactor in order toinitiate polymerization of the isoprene. The reaction is allowed to runfor one hour, after which 121 grams of purified butadiene is pressuredinto the reactor at a rate such that the reaction temperature does notexceed 70° C. After one hour, 0.87 mL of acetic acid (15.2 mmol) isinjected into the reactor to quench the living anion. The mixture iscooled to room temperature and filtered through alumina/Celite. Ananti-oxidant Irganox 1076 from Ciba-Geigy (100 ppm based on dry polymer)is added and the solvent removed under reduced pressure to yield aclear, colorless, viscous fluid. The number average molecular weight ofthe prepared polymer is 10,000.

Example II Selective Hydrogenation of the Polymer of Example I

The polymer solution from Example I is subjected to a selectivehydrogenation procedure using a catalyst prepared by mixingdiethylaluminum ethoxide and cobalt octoate (3.5 to 1 molar ratio) andfollowing the general procedures outlined in Example VI of U.S. Pat. No.5,633,415. The extent of hydrogenation is followed by FTIR and iscontinued until no absorption remains at 910 cm⁻¹ and 990 cm⁻¹ (−1,2polybutadiene structure), and essentially no residual trans double bondsare present as seen by disappearance of the 968 cm⁻¹ absorption. TheFTIR analysis of the polymers at the end of the selective hydrogenationtypically indicates 0 to 10 trans polybutadiene double bonds and 50 to100 vinylidene (−3, 4 polyisoprene) double bonds remain—normalized to100,000 molecular weight polymer chain. The polymer of Example 1 has 0to 1 residual trans double bonds and 5 to 10 vinylidene double bonds(for subsequent functionalization).

The hydrogenation catalyst is removed by washing, as described in U.S.Pat. No. 5,633,415, or by a filtration procedure preceded byprecipitation of the catalyst with essentially stoichiometric levels ofacetic acid and hydrogen peroxide. After catalyst removal, the polymeris isolated by removal of the solvent under reduced pressure.

Example III Maleic Modification of the Polymer of Example II

The polymer of Example II is dissolved in a diluent oil (e.g. lowviscosity mineral oil or polyalphaolefin) to give fluid concentratehaving 50% polymer content. The concentrate is reacted with an excess ofmaleic anhydride (110 to 150%) to give an acid number (based on neatpolymer) of approximately 35-40. This is equivalent to 6-7% maleicadduction to the polymer chain. The reaction is performed atapproximately 200° C. and is monitored by FTIR and/or acid numbertitration of stripped samples. The time required for reaction istypically 3 to 20 hours. After reaction, any residual maleic anhydrideis removed by vacuum stripping of the oil concentrate. The succinicanhydride modified polymer is obtained and is next treated with apolyamine to form a dispersant of this invention.

Example IV Reaction of the Polymers of Example III with a Polyamine

The polymer of Example III is reacted with aminopropyl morpholine (APM)(1 mole per mole of anhydride) at elevated temperatures (100-200° C.) toform a morpholino propyl succinimide adduct. Progress of the reaction isfollowed by monitoring water reaction product volume as well asdisappearance of succinic anhydride absorption in FTIR coupled withappearance of typical imide absorption at about 1705 cm⁻¹. Any excessamine is removed by vacuum distillation and completeness of the reactionis confirmed by acid number titration (should be zero) and determinationof total base number (TBN) by perchloric acid titration. A typical TBNvalue for the imidized polymer is 35 (based on neat polymer). The numberof functional imides per molecule varies with molecular weight, and istypically:

Typical Functional groups per Approximate M.W. molecule 5000⁺   3-3.510000⁺ 6-7 15000⁺   9-10.5 20000⁺ 12-14

For ease of handling, the higher molecular weight polymers above 15,000can be further diluted with oil.

Thus, while there have been described what are presently believed to bethe preferred embodiments of the present invention, those skilled in theart will realize that other and further embodiments can be made withoutdeparting from the spirit of the invention, and it is intended toinclude all such further modifications and changes as come within thetrue scope of the claims set forth herein.

What is claimed is:
 1. A dispersant substance for modifying thedispersancy or viscometric properties of a fluid, comprising: a liquidcopolymer of a first conjugated diene, a second conjugated diene and anaryl-substituted olefin, wherein: said first conjugated diene comprisesat least one relatively more substituted conjugated diene having atleast five carbon atoms and the formula:

wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that atleast one of R¹-R⁶ is a hydrocarbyl group, provided that afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (1) has the formula:

wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups;and said second conjugated diene comprises at least one relatively lesssubstituted conjugated diene different from the first conjugated dieneand having at least four carbon atoms and the formula:

wherein R⁷-R¹² are each hydrogen or a hydrocarbyl group, provided thatafter polymerization, the unsaturation of the polymerized conjugateddiene of formula (3) has the formula:

wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group; and wherein the copolymerhas been functionalized by a method comprising: selectivelyhydrogenating the copolymer to provide a selectively hydrogenatedcopolymer; and functionalizing said selectively hydrogenated copolymerto provide a functionalized copolymer having at least one polarfunctional group.
 2. The dispersant substance of claim 1, wherein saidaryl-substituted olefin is selected from the group consisting ofstyrene, alkylated styrene, vinyl naphthalene and alkylated vinylnaphthalene.
 3. The dispersant substance of claim 2, wherein saidaryl-substituted olefin is styrene.
 4. The dispersant substance of claim1, wherein said functionalized copolymer is modified, by reaction with aLewis base selected from the group consisting of a monoamine, polyamine,polyhydroxy compound, reactive polyether, or a combination thereof. 5.The dispersant substance of claim 4, wherein said polyamine comprises anaminopropylmorpholine.
 6. The dispersant substance of claim 1, whereinsaid functionalized copolymer is post treated with a post-treatingagent.
 7. The dispersant substance of claim 6, wherein saidpost-treating agent is a boron-containing compound.
 8. The dispersantsubstance of claim 1, wherein said first and second conjugated dienesare polymerized as a block copolymer comprising at least two alternatingblocks: (I)_(x)-(B)_(y) or (B)_(y)-(I)_(x) wherein: the block (I)comprises at least one polymerized conjugated diene of formula (1); theblock (B) comprises at least one polymerized conjugated diene of formula(3); x is the number of polymerized monomer units in block (I) and is atleast 1, and y is the number of polymerized monomer units in block (B)and is at least
 25. 9. The dispersant substance of claim 8, wherein saidblock (I) and/or block (B) comprises the aryl-substituted olefinincorporated randomly or as a block.
 10. The dispersant substance ofclaim 8, wherein each of the (B) blocks has from about 30% to about 90%of 1,2-subunits.
 11. The dispersant substance of claim 1, wherein saidfirst conjugated diene is included in said polymer in an amount of from1% to about 25% wt; and said second conjugated diene is included in saidpolymer in an amount of from about 75% wt. to about 99% wt.
 12. Thedispersant substance of claim 1, wherein after the selectivelyhydrogenating step, the Iodine Number for residual unsaturation offormula (2) is from about 50% to about 100% of the Iodine Number priorto the selectively hydrogenating step.
 13. The dispersant substance ofclaim 1, wherein after the selectively hydrogenating step, the IodineNumber for residual unsaturation of formula (4) is from about 0% toabout 10% of Iodine Number prior to the selectively hydrogenating step.14. The dispersant substance of claim 1, wherein the conjugated diene offormula (1) comprises isoprene and the conjugated diene of formula (3)comprisies 1,3-butadiene.
 15. The dispersant substance of claim 1,wherein said functionalizing step provides a functionalized polymerhaving at least one functional group selected from the group consistingof halogen groups, hydroxyl groups, epoxy groups, sulfonic acid groups,mercapto groups, acrylate groups, carboxyl groups, and mixtures thereof.16. The dispersant substance of claim 15, wherein said carboxyl groupscomprise maleic anhydride.
 17. The dispersant substance of claim 1,wherein said polymer is distributed in a carrier fluid to provide adispersant concentrate.
 18. The dispersant substance of claim 17,wherein said polymer is included in an amount of from 5% to about 90%wt. of the dispersant concentrate.
 19. The dispersant substance of claim1, further comprising at least one additive selected from the groupconsisting of antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, anti-foam agents,corrosion and rust inhibitors and viscosity index improvers.
 20. Adispersant-modified fluid having modified dispersancy or viscometricproperties comprising: a fluid; and a dispersant substance comprising; aliquid copolymer of a first conjugated diene and a second conjugateddiene and an aryl-substituted olefin, wherein: said first conjugateddiene comprises at least one relatively more substituted conjugateddiene having at least five carbon atoms and the formula:

wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that atleast one of R¹-R⁶ is a hydrocarbyl group, provided that afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (1) has the formula:

wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups;and said second conjugated diene comprises at least one relatively lesssubstituted conjugated diene different from the first conjugated dieneand having at least four carbon atoms and the formula:

wherein R⁷-R¹² are each hydrogen or a hydrocarbyl group, provided thatafter polymerization, the unsaturation of the polymerized conjugateddiene of formula (3) has the formula:

wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VIII) and R^(VIII) is a hydrocarbyl group; and wherein the copolymerhas been functionalized by a method comprising: selectivelyhydrogenating the copolymer to provide a selectively hydrogenatedcopolymer; and functionalizing said selectively hydrogenated copolymerto provide a functionalized copolymer having at least one polarfunctional group.
 21. The dispersant modified fluid of claim 20, whereinthe functionalized copolymer is modified, by reaction with a Lewis baseselected from the group consisting of a monoamine, polyamine,polyhydroxy compound, reactive polyether, or a combination thereof. 22.The dispersant-modified fluid of claim 20, wherein said aryl-substitutedolefin is selected from the group consisting of styrene, alkylatedstyrene, vinyl naphthalene and alkylated vinyl naphthalene.
 23. Thedispersant-modified fluid of claim 20, wherein said aryl-substitutedolefin is styrene.
 24. The dispersant-modified fluid of claim 20,wherein said functionalized copolymer is post treated with apost-treating agent.
 25. The dispersant-modified fluid of claim 20,wherein said dispersant substance is included in an amount of from about0.001% wt. to about 20% wt.
 26. The dispersant-modified fluid of claim20, wherein said dispersant substance is included in an amount of fromabout 0.1% wt. to about 10% wt.
 27. The dispersant-modified fluid ofclaim 20, wherein said dispersant substance is included in an amount offrom about 0.5% wt. to about 5% wt.
 28. The dispersant-modified fluid ofclaim 20, wherein said fluid is naturally occurring, synthetic or acombination thereof.
 29. The dispersant-modified fluid of claim 20,wherein said fluid is selected from the group consisting of motor oils,transmission fluids, hydraulic fluids, gear oils, aviation oils,greases, normally liquid fuels, and lubricants.
 30. Thedispersant-modified fluid of claim 20, wherein said fluid furthercomprises at least one additive selected from the group consisting ofantioxidants, pour point depressants, detergents, dispersants, frictionmodifiers, anti-wear agents, anti-foam agents, corrosion and rustinhibitors, and viscosity index improvers.